use ES_PLUGINS env variable to Install external plugin to elastic docker at the time of start

[ajaykumar4]

Fixes #75864
use ES_PLUGINS env variable to Install external plugin to elastic docker at the time of start

[cla-checker-service]

❌ Author of the following commits did not sign a Contributor Agreement:
0df3d62

Please, read and sign the above mentioned agreement if you want to contribute to this project

[ajaykumar4]

I have signed CLA agreement, even then it is failing

[jasontedor]

Thanks for the contribution. However, see #70219. I think we want a solution broader than the one here, that applies also to the non-Docker images.

[ajaykumar4]

@jasontedor so do i need to close this PR and issue

[pugnascotia]

@ajaykumar4 yes, thank you for your contribution 🙏 but as Jason says, we're going to address this more comprehensively.